Temperature effects on community size structure: The value of large-scale biomonitoring programs

Abstract

The effects of climate warming on individuals and populations are becoming increasingly apparent (e.g. changes in body mass, species range shifts); however, impacts at higher levels of biological organization (i.e. communities and ecosystems) are less understood (Heneghan et al., 2019). Ecological communities comprise many small- and few large-sized individuals. The individual size distribution—the frequency distribution of individual body sizes (White et al., 2007; Figure 1)—represents a key measure of community structure, signifying the relative number of large versus small organisms (Perkins et al., 2019). Where organisms occupy different trophic levels, the power-law exponent that underpins the individual size distribution (ISD exponent, henceforth) represents the efficiency of energy transfer from small, abundant prey to fewer large predators (Brown et al., 2004). As such, the individual size distribution provides a lens through which to understand the effects of multiple aspects of climatic (and general environmental) change on energy flow in natural systems (Heneghan et al., 2019; Petchey & Belgrano, 2010). A study by Pomeranz et al. in this issue provides clear focus on how this measure of community size structure varies with temperature at the continental scale.